Blaming Fecundity issues on sports fishing is like blaming it on large mesh gill nets that let sockeye and small chinook though but only catch the large chinook.
From a book written in 1919. A few years prior the seine fishery almost completely wiped out CR chinook.
Campbell River is the headquarters for the big tyee salmon and ranks with Cowichan River as world famous fishing water. A few years ago during the month of August you would find scores of fishermen there from all parts of the globe, having come especially to land some of the monster salmon that yearly come to the river to spawn. In those days it was not considered anything much to land two or three fish between forty and fifty pounds with several cohoes in addition before breakfast. Unless a fish was sixty pounds or over, it attracted very little attention. Apart from the pleasure of fishing it was well worth any body's while to go there for a few days and meet men from all over the world and just to watch the fishing whenever there was a favourable tide. You might, perhaps, see as many as sixty boats all fishing at the mouth of the river, with a few Indians in canoes in addition. There would be men, women, and often children, with every conceivable form of tackle, some with hand lines only, others with huge eighteen foot salmon fly rods and many Americans with six-foot tarpon rods, with wonderful multiplying reels. Yon would likely see half a dozen boats all playing "tyees" at the same time, some of them in an agony of fear that some other boat would foul them and shrieking wild, and often strong warnings to boats in their vicinity. There would be smashed tackle and broken rods and narrow escapes from falling overboard and occasionally the sight of a novice man fully playing what he believed to be a record salmon, but in reality the bottom. Then, later in the evening when fishing was over and the inner man refreshed with meat and drink (prohibition was not even thought of in those days) there would be a gathering and events of the day discussed, with the usual stories of record fish lost, etc. Those were great days: they brought the fisherman much pleasure and the Province much profit.' .Alas! the glory of them has departed; commercial fishermen with their traps and seines have unwisely been allowed to ruin the most famous salmon water ever known.